Allely, Clare S., Minnis, Helen, Thompson, Lucy, Wilson, Philip, and Gillberg, Christopher (2014) Neurodevelopmental and psychosocial risk factors in serial killers and mass murderers. Aggression and Violent Behavior, 19 (3). pp. 288-301. ISSN 1359-1789 Copyright © 2014 The Authors http://eprints.gla.ac.uk/93426/ Deposited on: 23 June 2014 Enlighten – Research publications by members of the University of Glasgow http://eprints.gla.ac.uk Aggression and Violent Behavior 19 (2014) 288–301 Contents lists available at ScienceDirect Aggression and Violent Behavior Neurodevelopmental and psychosocial risk factors in serial killers and mass murderers Clare S. Allely a, Helen Minnis a,⁎,LucyThompsona, Philip Wilson b, Christopher Gillberg c a Institute of Health and Wellbeing, University of Glasgow, RHSC Yorkhill, Glasgow G3 8SJ, Scotland, United Kingdom b Centre for Rural Health, University of Aberdeen, The Centre for Health Science, Old Perth Road, Inverness IV2 3JH, Scotland, United Kingdom c Gillberg Neuropsychiatry Centre, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden article info abstract Article history: Multiple and serial murders are rare events that have a very profound societal impact. We have conducted a Received 11 July 2013 systematic review, following PRISMA guidelines, of both the peer reviewed literature and of journalistic and Received in revised form 20 February 2014 legal sources regarding mass and serial killings. Our findings tentatively indicate that these extreme forms of vi- Accepted 8 April 2014 olence may be a result of a highly complex interaction of biological, psychological and sociological factors and Available online 18 April 2014 that, potentially, a significant proportion of mass or serial killers may have had neurodevelopmental disorders such as autism spectrum disorder or head injury. Research into multiple and serial murders is in its infancy: Keywords: fi Autistic Spectrum Disorder there is a lack of rigorous studies and most of the literature is anecdotal and speculative. Speci c future study Serial killer of the potential role of neurodevelopmental disorders in multiple and serial murders is warranted and, due to Mass murder the rarity of these events, innovative research techniques may be required. Brain injury © 2014 The Authors. Published by Elsevier Ltd. Psychosocial stressors Contents 1. Introduction.............................................................. 289 1.1. Prevalenceofmultiplehomicide................................................. 289 1.2. Autismspectrumdisorders(ASDs)................................................ 289 1.3. Psychosocialmediators...................................................... 290 1.4. Sexualdeviancyandfantasies................................................... 290 1.5. Neurochemistryofviolence.................................................... 290 1.6. Evolutionarypsychologyperspectiveofviolence.......................................... 290 2. Methods................................................................ 291 3. Results................................................................ 292 3.1. ASDwithevidenceofheadinjuryanalysis............................................. 293 3.2. Casestudy:JeffreyDahmer.................................................... 293 3.3. HeadinjurywithpossibleASDtraitsanalysis............................................ 295 3.4. Case study: Richard Ramirez —“night stalker” ........................................... 295 4. Discussion............................................................... 296 5. Conclusionsandrecommendations.................................................... 297 Disclosurestatement............................................................ 298 Acknowledgments.............................................................. 298 References.................................................................. 298 ⁎ Corresponding author at: Institute of Health and Wellbeing, University of Glasgow, Caledonia House, Royal Hospital for Sick Children, Yorkhill, Glasgow G3 8SJ, United Kingdom. Tel.: +44 141 201 9239. E-mail addresses: [email protected] (C.S. Allely), [email protected] (H. Minnis), [email protected] (L. Thompson), [email protected] (P. Wilson), [email protected] (C. Gillberg). http://dx.doi.org/10.1016/j.avb.2014.04.004 1359-1789/© 2014 The Authors. Published by Elsevier Ltd. C.S. Allely et al. / Aggression and Violent Behavior 19 (2014) 288–301 289 “I am relieved to see this verdict. The temptation for people to fob various psychosocial and biological factors in the etiology of these him off as a madman has now gone.” Survivor of Anders Breivik events and research findings offer conflicting evidence. For example, shooting in Norway. in a retrospective study of the forensic psychiatric evaluations of 57 adolescent offenders accused of a homicide, 64% had developmental problems. Yet, use of multiple and excessive violence was not related 1. Introduction to having developmental problems (Hagelstam & Häkkänen, 2006). Söderström (2005) also found that childhood-onset neuropsychiatric The question as to why anyone would wish to kill large numbers of disorders were common among violent offenders. Most frequent were their fellow human beings is unanswered and debates around predis- disruptive behavior disorders, such as ADHD and conduct disorder, posing and precipitating factors continue. We have systematically but a substantial minority had ASDs, tic disorders and mental retarda- reviewed the literature regarding mass and serial killing. These are tion/learning disabilities (Söderström, 2005). rare events and, consequently, the peer reviewed literature is sparse We consider some of these psychosocial and neurodevelopmental and leads to conflicting findings. A systematic review is warranted for risk factors below. Silva, Leong, and Ferrari (2004) suggest the presence two reasons: first, despite their rarity, these events have a profound of an association between ASD and serial homicidal behavior which has impact on societies, second, a clearer understanding of the antecedents also been suggested by others (e.g., Fitzgerald, 2001). This has led us to of these events may help elucidate the mechanisms of extreme violence, explore the phenomenon of serial and mass killings in relation to these potentially leading to preventative strategies. risk factors in a unique systematic review of the literature. To examine Murder is the killing of one person by another person with “malice ASD as a risk factor is particularly timely given the recent shooting aforethought”; there may or may not be premeditation. Generally, a cases of Adam Lanza, James Holmes, and Anders Brievik, all of person who murders restricts his or her act to one victim. A mass mur- whom have been considered to have autistic features (http://www. derer, however, kills three or more victims over a short period of time — zerohedge.com/news/2012-12-15/newtown-shooter-had- typically hours but sometimes over days (http://www.encyclopedia. asperger-syndrome-and-some-us-gun-facts; http://www.dailymail. com/doc/1G2-3407200189.html). In contrast, serial killers murder co.uk/news/article-2156530/Anders-Behring-Breivik-rare-forms- their victims separately and over a period of time, with a cooling-off Aspergers-Tourette-s-syndromes-says-Norways-leading-psychiatrist. period between murders. Traditionally, a serial killer is defined as an in- html). Fitzgerald (2010) has suggested that Autistic Psychopathy may dividual who has killed three or more people (Holmes & Holmes, 2010). underlie the motivation of some of these serial killers. He suggests Serial killing may continue for years until the perpetrator is caught or a new diagnosis Criminal Autistic Psychopathy, a subcategory of turns himself/herself in to the authorities (http://www.encyclopedia. Asperger's syndrome. com/doc/1G2-3407200189.html). In addition to ASD, we also explored head injury as it has been shown that this is more prevalent in serial killers, with one study sug- 1.1. Prevalence of multiple homicide gesting that one in four serial killers had suffered either a head injury or (more rarely) a condition affected the brain — such as meningitis dur- Attempts to estimate the numbers of serial murder victims have var- ing their early years (Stone, 2009). However, this has rarely been inves- ied greatly (Quinet, 2007). This may have resulted from several factors tigated in the peer reviewed literature and it typically only explored (Jenkins, 2005): when apprehended, serial killers may overestimate using samples of single homicide cases. Certainly the combined effects the number of their victims (Fox & Levin, 2005; Quinet, 2007); gaining of psychosocial stressors, head injury, and ASD have never previously access to serial killers in order to conduct research interviews is difficult been examined in a systematic review. (Silvio, McCloskey, & Ramos-Grenier, 2006) and incidence and preva- After an extensive review, we found very little mention of Attention lence of serial murder is difficult to determine, since accurate statistics Deficit Hyperactivity Disorder (ADHD) in the literature and biographies are not kept (Brantley & Kosky, 2005; Myers, Reccoppa, Burton, & of killers (Stone, 2009). Once notable exception to this was an autobiog- McElroy, 1993; Schlesinger, 1998). A further challenge is that there is raphy of serial killer Richard Ramirez who had ADHD as a child (Carlo, no single, generally accepted definition for serial homicide